[PATCH 4.9 005/130] IB/mlx5: Fix reported max SGE calculation

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eli Cohen <eli@xxxxxxxxxxxx>

commit 288c01b746aab484651391ca6d64b585d3eb5ec6 upstream.

Add the 512 bytes limit of RDMA READ and the size of remote
address to the max SGE calculation.

Fixes: e126ba97dba9 ('mlx5: Add driver for Mellanox Connect-IB adapters')
Signed-off-by: Eli Cohen <eli@xxxxxxxxxxxx>
Signed-off-by: Maor Gottlieb <maorg@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/infiniband/hw/mlx5/main.c |    8 +++++---
 drivers/infiniband/hw/mlx5/qp.c   |   29 ++++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 4 deletions(-)

--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -496,6 +496,7 @@ static int mlx5_ib_query_device(struct i
 	struct mlx5_ib_dev *dev = to_mdev(ibdev);
 	struct mlx5_core_dev *mdev = dev->mdev;
 	int err = -ENOMEM;
+	int max_sq_desc;
 	int max_rq_sg;
 	int max_sq_sg;
 	u64 min_page_size = 1ull << MLX5_CAP_GEN(mdev, log_pg_sz);
@@ -618,9 +619,10 @@ static int mlx5_ib_query_device(struct i
 	props->max_qp_wr	   = 1 << MLX5_CAP_GEN(mdev, log_max_qp_sz);
 	max_rq_sg =  MLX5_CAP_GEN(mdev, max_wqe_sz_rq) /
 		     sizeof(struct mlx5_wqe_data_seg);
-	max_sq_sg = (MLX5_CAP_GEN(mdev, max_wqe_sz_sq) -
-		     sizeof(struct mlx5_wqe_ctrl_seg)) /
-		     sizeof(struct mlx5_wqe_data_seg);
+	max_sq_desc = min_t(int, MLX5_CAP_GEN(mdev, max_wqe_sz_sq), 512);
+	max_sq_sg = (max_sq_desc - sizeof(struct mlx5_wqe_ctrl_seg) -
+		     sizeof(struct mlx5_wqe_raddr_seg)) /
+		sizeof(struct mlx5_wqe_data_seg);
 	props->max_sge = min(max_rq_sg, max_sq_sg);
 	props->max_sge_rd	   = MLX5_MAX_SGE_RD;
 	props->max_cq		   = 1 << MLX5_CAP_GEN(mdev, log_max_cq);
--- a/drivers/infiniband/hw/mlx5/qp.c
+++ b/drivers/infiniband/hw/mlx5/qp.c
@@ -351,6 +351,29 @@ static int calc_send_wqe(struct ib_qp_in
 		return ALIGN(max_t(int, inl_size, size), MLX5_SEND_WQE_BB);
 }
 
+static int get_send_sge(struct ib_qp_init_attr *attr, int wqe_size)
+{
+	int max_sge;
+
+	if (attr->qp_type == IB_QPT_RC)
+		max_sge = (min_t(int, wqe_size, 512) -
+			   sizeof(struct mlx5_wqe_ctrl_seg) -
+			   sizeof(struct mlx5_wqe_raddr_seg)) /
+			sizeof(struct mlx5_wqe_data_seg);
+	else if (attr->qp_type == IB_QPT_XRC_INI)
+		max_sge = (min_t(int, wqe_size, 512) -
+			   sizeof(struct mlx5_wqe_ctrl_seg) -
+			   sizeof(struct mlx5_wqe_xrc_seg) -
+			   sizeof(struct mlx5_wqe_raddr_seg)) /
+			sizeof(struct mlx5_wqe_data_seg);
+	else
+		max_sge = (wqe_size - sq_overhead(attr)) /
+			sizeof(struct mlx5_wqe_data_seg);
+
+	return min_t(int, max_sge, wqe_size - sq_overhead(attr) /
+		     sizeof(struct mlx5_wqe_data_seg));
+}
+
 static int calc_sq_size(struct mlx5_ib_dev *dev, struct ib_qp_init_attr *attr,
 			struct mlx5_ib_qp *qp)
 {
@@ -387,7 +410,11 @@ static int calc_sq_size(struct mlx5_ib_d
 		return -ENOMEM;
 	}
 	qp->sq.wqe_shift = ilog2(MLX5_SEND_WQE_BB);
-	qp->sq.max_gs = attr->cap.max_send_sge;
+	qp->sq.max_gs = get_send_sge(attr, wqe_size);
+	if (qp->sq.max_gs < attr->cap.max_send_sge)
+		return -ENOMEM;
+
+	attr->cap.max_send_sge = qp->sq.max_gs;
 	qp->sq.max_post = wq_size / wqe_size;
 	attr->cap.max_send_wr = qp->sq.max_post;